1. Field of the Invention
The present invention relates to an ink-jet head, a method of production of the ink-jet head, and an ink-jet printing system including the ink-jet head.
2. Description of the Related Art
Ink-jet printing systems are commonly used in various image forming systems, such as printers, facsimiles, copiers and plotters, to perform a printing process in which an image is printed on a recording medium (e.g., paper). Generally, an electrostatic ink-jet head is provided in such an ink-jet printing system. The ink-jet head of this type normally includes a nozzle which discharges an ink drop onto recording paper, a discharging chamber which communicates with the nozzle and contains ink therein, an oscillation plate which is provided to define a bottom of the discharging chamber and pressurizes the ink in the discharging chamber when the oscillation plate is actuated, and an electrode which is provided to face the oscillation plate via a gap between the oscillation plate and the electrode.
Upon application of a driving voltage to the electrode, the electrode actuates the oscillation plate by electrostatic force, so that the ink-jet head ejects an ink drop from the nozzle onto the recording paper by pressurizing the ink in the discharging chamber. The discharging chamber of the ink-jet head may be also called a pressure chamber, a pressurizing chamber, a fluid chamber or an ink passage.
In the above-described ink-jet head, the mechanical deflection characteristics of the oscillation plate significantly affect the ink discharging characteristics of the head. In order to achieve the desired ink discharging characteristics, it is needed to provide a thin-film structure of the oscillation plate having high accuracy, and to provide highly accurate dimension of the gap between the oscillation plate and the electrode.
For example, Japanese Laid-Open Patent Application Nos. 6-23986 and 6-71882 disclose an improved oscillation plate for use in an electrostatic ink-jet head. In the ink-jet head disclosed in the above documents, a boron diffusion layer in which a high concentration of boron is diffused is formed on a silicon substrate on which the oscillation plate is provided. By performing the anisotropic etching on the silicon substrate, the oscillation plate having the boron diffusion layer with the high concentration of boron is formed on the silicon substrate.
In order to provide highly accurate dimension of the gap between the oscillation plate and the electrode, Japanese Laid-Open Patent Application Nos. 6-23986 and 9-267479 disclose that a silicon substrate for forming the oscillation plate thereon and a silicon substrate for forming the electrode thereon are bonded together at a temperature around 1100 deg. C. The direct bonding method is known as the method for creating highly reliable and rigid adhesion, and it is commonly used for the manufacture of a silicon-on-insulator (SOI) wafer. The above-mentioned direct bonding method is performed at a high temperature in a range of 1100 deg. C. to 1200 deg. C., and the silicon dioxide film on the substrate is melted so that a highly reliable and rigid adhesion of the two silicon substrates is created.
However, in the conventional ink-jet head disclosed in the above documents, the direct bonding method must be performed at a high temperature in the range of 1100 deg. C. to 1200 deg. C. The manufacturing equipment for bonding the silicon substrates becomes bulky and complicated while the temperature management is required. Hence, the manufacturing cost of ink-jet head will be increased. Further, when forming the oscillation plate by etching after the direct bonding method is performed, the components on the electrode substrate require a high temperature resistance to withstand the high-temperature bonding. The source materials of the components on the electrode substrate are limited due to the requirement of temperature resistance.
Further, in the conventional ink-jet head disclosed in the above documents, when forming the oscillation plate having the boron diffusion layer with a high concentration of boron, on the silicon substrate, the re-distribution of boron over the oscillation plate is caused by the high-temperature heating during the direct bonding. This will produce variation of the thickness of the oscillation plate, variation of the ink discharging characteristics of the head, or lowering of the concentration of boron in the boron diffusion layer. In such cases, it is very difficult to form the oscillation plate having high accuracy.
Japanese Laid-Open Patent Application Nos. 5-50601 and 6-71882 disclose an electrostatic ink-jet head in which the recessed portions of the oscillation plate and/or the electrode, or the alternative silicon dioxide films, are formed the bonding surfaces of the oscillation plate substrate and/or the electrode substrate. The conventional ink-jet head disclosed in the above documents effectively maintains the gap between the oscillation plate and the electrode at a given distance. However, it is difficult to provide reliable ink discharging characteristics and low manufacturing cost of the head.
Japanese Laid-Open Patent Application No. 9-286101 discloses an ink-jet head production method in which the oscillation plate substrate and the electrode substrate are bonded together by an anodic bonding process. However, it is difficult to provide reliable ink discharging characteristics and low manufacturing cost of the head.
Japanese Laid-Open Patent Application No. 10-286954 discloses an ink-jet head production method in which the oscillation plate substrate and the electrode substrate are bonded together by forming a polysilazan layer on the bonding surfaces of the two silicon substrates. However, steam or other gases may be produced out of the polysilazan layer, and it is difficult to provide reliable ink discharging characteristics and low manufacturing cost of the head.
Japanese Laid-Open Patent Application No. 6-8449 discloses an ink-jet head production method using the direct bonding in which the oscillation plate substrate and the electrode substrate are directly bonded together. However, it is difficult to provide reliable ink discharging characteristics and low manufacturing cost of the head.
An object of the present invention is to provide an improved ink-jet head in which the above-described problems are eliminated.
Another object of the present invention is to provide an ink-jet head that enables the direct bonding method to be performed at a comparatively low temperature and with reliability and provides an accurate and dense configuration of the components of the ink-jet head.
Another object of the present invention is to provide an ink-jet head that provides reliable ink discharging characteristics and low manufacturing cost.
Another object of the present invention is to provide a method of production of an ink-jet head, which provides reliable ink discharging characteristics and low manufacturing cost of the ink-jet head.
Another object of the present invention is to provide an ink-jet printing system including an ink-jet head that provides reliable ink discharging characteristics and low manufacturing cost.
The above-mentioned objects of the present invention are achieved by an ink-jet head comprising: a nozzle which discharges an ink drop to a recording medium; a discharging chamber which communicates with the nozzle and contains ink therein; an oscillation plate which is provided on a first substrate of silicon, the oscillation plate defining a bottom surface of the discharging chamber, the oscillation plate pressurizing the ink in the discharging chamber when the oscillation plate is actuated; and an electrode which is provided on a second substrate of silicon, the electrode facing the oscillation plate via a gap between the oscillation plate and the electrode, the electrode actuating the oscillation plate by electrostatic force upon application of a driving voltage to the electrode, wherein at least one of a first bonding area of the first substrate and a second bonding area of the second substrate is provided with a silicon oxide film, and the silicon oxide film contains boron on a surface thereof where the first substrate and the second substrate are bonded together.
The above-mentioned objects of the present invention are achieved by an ink-jet head comprising: a nozzle which discharges discharging an ink drop to a recording medium; a discharging chamber which communicates with the nozzle and contains ink therein; an oscillation plate which is provided on a first substrate of silicon, the oscillation plate defining a bottom surface of the discharging chamber, the oscillation plate pressurizing the ink in the discharging chamber when the oscillation plate is actuated; and an electrode which is provided on a second substrate of silicon, the electrode facing the oscillation plate via a gap between the oscillation plate and the electrode, the electrode actuating the oscillation plate by electrostatic force upon application of a driving voltage to the electrode, wherein the first substrate is bonded to the second substrate via a silicon oxide film, the silicon oxide film being provided to have a lowered melting point that allows the bonding of the first and second substrates at a temperature lower than 1000 deg. C.
The above-mentioned objects of the present invention are achieved by an ink-jet head comprising: a nozzle which discharges an ink drop to a recording medium; a discharging chamber which communicates with the nozzle and contains ink therein; an oscillation plate which is provided on a first substrate of silicon, the oscillation plate defining a bottom surface of the discharging chamber, the oscillation plate pressurizing the ink in the discharging chamber when the oscillation plate is actuated; and an electrode which is provided on a second substrate of silicon, the electrode facing the oscillation plate via a gap between the oscillation plate and the electrode, the electrode actuating the oscillation plate by electrostatic force upon application of a driving voltage to the electrode, wherein the first substrate is bonded to the second substrate via a silicon oxide layer, the silicon oxide layer containing phosphorus and/or boron on a surface thereof where the first substrate and the second substrate are bonded together.
The above-mentioned objects of the present invention are achieved by an ink-jet head comprising: a nozzle which discharges an ink drop to a recording medium; a discharging chamber which communicates with the nozzle and contains ink therein; an oscillation plate which is provided on a first substrate of silicon, the oscillation plate defining a bottom surface of the discharging chamber, the oscillation plate pressurizing the ink in the discharging chamber when the oscillation plate is actuated; an electrode which is provided on a second substrate of silicon, the electrode facing the oscillation plate via a gap between the oscillation plate and the electrode, the electrode actuating the oscillation plate by electrostatic force upon application of a driving voltage to the electrode; and a spacer which is provided on the second substrate such that the spacer forms the gap between the oscillation plate and the electrode, the spacer having a silicon oxide layer where the first substrate is bonded to the second substrate via the spacer, the silicon oxide layer being provided to have a lowered melting point that allows the bonding of the first substrate and the second substrate at a temperature lower than 1000 deg. C.
The above-mentioned objects of the present invention are achieved by an ink-jet head comprising: a nozzle which discharges an ink drop to a recording medium; a discharging chamber which communicates with the nozzle and contains ink therein; an oscillation plate which is provided on a first substrate of silicon, the oscillation plate defining a bottom surface of the discharging chamber, the oscillation plate pressurizing the ink in the discharging chamber when the oscillation plate is actuated; an electrode which is provided on a second substrate of silicon, the electrode facing the oscillation plate via a gap between the oscillation plate and the electrode, the electrode actuating the oscillation plate by electrostatic force upon application of a driving voltage to the electrode; and a spacer which is provided on the second substrate such that the spacer forms the gap between the oscillation plate and the electrode, the spacer having a silicon oxide layer thereon, the silicon oxide layer containing phosphorus and/or boron on a surface thereof where the first substrate is bonded to the second substrate via the spacer.
The above-mentioned objects of the present invention are achieved by an ink-jet head comprising: a nozzle which discharges an ink drop to a recording medium; a discharging chamber which communicates with the nozzle and contains ink therein; an oscillation plate which is provided on a first substrate of silicon, the oscillation plate defining a bottom surface of the discharging chamber, the oscillation plate pressurizing the ink in the discharging chamber when the oscillation plate is actuated; an electrode which is provided on a second substrate of silicon, the electrode facing the oscillation plate via a gap between the oscillation plate and the electrode, the electrode actuating the oscillation plate by electrostatic force upon application of a driving voltage to the electrode; and a spacer which is provided on the second substrate such that the spacer forms the gap between the oscillation plate and the electrode, the spacer having a silicon oxide film on a surface thereof where the first substrate is bonded to the second substrate via the spacer, and a dummy groove being provided on the silicon oxide film.
The above-mentioned objects of the present invention are achieved by an ink-jet head comprising: a nozzle which discharges an ink drop to a recording medium; a discharging chamber which communicates with the nozzle and contains ink therein; an oscillation plate which is provided on a first substrate of silicon, the oscillation plate defining a bottom surface of the discharging chamber, the oscillation plate pressurizing the ink in the discharging chamber when the oscillation plate is actuated; an electrode which is provided on a second substrate of silicon, the electrode facing the oscillation plate via a gap between the oscillation plate and the electrode, the electrode actuating the oscillation plate by electrostatic force upon application of a driving voltage to the electrode; and a spacer which is provided on the second substrate such that the spacer forms the gap between the oscillation plate and the electrode, the spacer having a silicon oxide layer on a surface thereof where the first substrate is bonded to the second substrate via the spacer, wherein a dummy electrode is provided on a base layer of the silicon oxide layer.
The above-mentioned objects of the present invention are achieved by a method of production of an ink-jet head, the ink-jet head including a nozzle discharging an ink drop to a recording medium, a discharging chamber communicating with the nozzle and containing ink therein, an oscillation plate provided on a first substrate of silicon, the oscillation plate defining a bottom surface of the discharging chamber, and an electrode provided on a second substrate of silicon, the electrode facing the oscillation plate via a gap between the oscillation plate and the electrode, the method comprising the steps of: providing a silicon oxide layer on one of the first substrate and the second substrate, the silicon oxide layer containing phosphorus and/or boron on a surface thereof where the first substrate and the second substrate are bonded together; thermally treating the silicon oxide layer at a temperature above a softening point of the silicon oxide layer; and bonding the first substrate to the second substrate via the silicon oxide layer at a temperature that is lower than the temperature of the thermal treatment step.
The above-mentioned objects of the present invention are achieved by a method of production of an ink-jet head, the ink-jet head including a nozzle discharging an ink drop to a recording medium, a discharging chamber communicating with the nozzle and containing ink therein, an oscillation plate provided on a first substrate of silicon, the oscillation plate defining a bottom surface of the discharging chamber, and an electrode provided on a second substrate of silicon, the electrode facing the oscillation plate via a gap between the oscillation plate and the electrode, the method comprising the steps of: providing a silicon oxide layer on one of the first substrate and the second substrate, the silicon oxide layer containing phosphorus and/or boron on a surface thereof where the first substrate and the second substrate are bonded together; thermally treating the silicon oxide layer at a temperature above a softening point of the silicon oxide layer; and bonding the first substrate to the second substrate via the silicon oxide layer at a temperature that is lower than the temperature of the thermal treatment step.
The above-mentioned objects of the present invention are achieved by an ink-jet printing system in which an ink-jet head is provided, the ink-jet head comprising: a nozzle which discharges an ink drop to a recording medium; a discharging chamber which communicates with the nozzle and contains ink therein; an oscillation plate which is provided on a first substrate of silicon, the oscillation plate defining a bottom surface of the discharging chamber, the oscillation plate pressurizing the ink in the discharging chamber when the oscillation plate is actuated; and an electrode which is provided on a second substrate of silicon, the electrode facing the oscillation plate via a gap between the oscillation plate and the electrode, the electrode actuating the oscillation plate by electrostatic force upon application of a driving voltage to the electrode, wherein the first substrate is bonded to the second substrate via a silicon oxide layer, the silicon oxide layer containing phosphorus and/or boron on a surface thereof where the first substrate and the second substrate are bonded together.
The above-mentioned objects of the present invention are achieved by an ink-jet printing system in which an ink-jet head is provided, the ink-jet head comprising: a nozzle which discharges an ink drop to a recording medium; a discharging chamber which communicates with the nozzle and contains ink therein; an oscillation plate which is provided on a first substrate of silicon, the oscillation plate defining a bottom surface of the discharging chamber, the oscillation plate pressurizing the ink in the discharging chamber when the oscillation plate is actuated; an electrode which is provided on a second substrate of silicon, the electrode facing the oscillation plate via a gap between the oscillation plate and the electrode, the electrode actuating the oscillation plate by electrostatic force upon application of a driving voltage to the electrode; and a spacer which is provided on the second substrate such that the spacer forms the gap between the oscillation plate and the electrode, the spacer having a silicon oxide layer on a surface thereof where the first substrate is bonded to the second substrate via the spacer.
In the ink-jet head of the present invention, at least one of the first bonding area of the first substrate and the second bonding area of the second substrate is provided with the silicon oxide film, and the silicon oxide film contains boron on a surface thereof where the first substrate and the second substrate are bonded together. The ink-jet head of the present invention and the production method thereof are effective in providing reliable ink discharging characteristics and low manufacturing cost. The ink-jet head of the present invention and the production method thereof enable the direct bonding of the first substrate and the second substrate at a low temperature and with reliability, and is effective in providing an accurate and dense configuration of the components of the ink-jet head.